In contrast to a few follicles arranged in a wedge-shaped segment at the periphery of a lymph node, a significant amount of thyroid tissue in a cervical lymph node is considered evidence of metastatic thyroid carcinoma. In a consecutive series of 243 patients with papillary carcinomas, 52 presented with lateral cervical masses that proved to be lymph nodes with metastatic thyroid carcinoma, in the absence of readily palpable thyroid nodularity. The metastatic disease was demonstrated by excisional biopsy in 40 patients and fine needle aspiration cytology in 12 patients. Thirty-two (of the 52) underwent further diagnostic work-up, consisting of radionuclide scintigraphy and ultrasonography, with the demonstration of abnormalities consistent with a thyroid neoplasm in 75 per cent (24/32) of these patients. The remaining 20 patients had no additional studies except for chemical thyroid function evaluation. The operative treatment in all 52 patients was total thyroidectomy and unilateral or bilateral modified neck dissections, when extensive cervical adenopathy was encountered. Papillary thyroid carcinoma, ranging in size from 2 to 14 mm, was found in the lobe ipsilateral to the presenting cervical node metastasis, in all specimens. In addition, contralateral cervical lymph node metastases were found in five (10%) of these patients, with no evidence of thyroid carcinoma in the corresponding thyroid lobe. With a mean follow-up period of 9 years, all patients are alive with no evidence of recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)